If there is an increase in the use of Green Roof Technology in our towns and cities the result will be an improved environment for the inhabitants.
Please discuss.....

Many very plausible benefits are listed here:

http://www.livingroofs.org/livingpages/benwaterunoff.html

With some sources cited.

As Nick says, repeated on the living roofs site, what you get out depends on what you put in. Having tracked the debate on green roofs I would say that in an urban environment there would be a tangible environmental improvement even if there were just a few dotted around. Could be as simple, at low densities, as "look at that nice green roof" - so called intellectual green space access.

S.

The answer is yes but it is too expensive a way to do it and it is a minuscule proportion that gets done

Planting trees would be a better idea

I am not sold on there 'insulation and temperature control', but the could help with short term water retention which could alleviate some local flooding (mainly due to old drains). Tended gardens often have higher biodiversity than either wilderness or monoculture, but it does depend on what is grown and attracted to them. You don't want seagulls and pigeons. My garden has a fairly tame robin, but nothing else when he is about.
I do think they can look good though.
One problem could be watering if the doomsayers of climate change are to be believed, the areas of highest populations are the ones with most water stress in the UK.

If you want to reduce energy consumption then get a shiny roof and as Tony says, plant a tree or ten.
If anyone can think up a decent experiment to test a green roof, I am willing to get involved as I do think it is interesting, had a little go last year, but it was very small scale.

Elder grows anywhere

But Gavin joining the debate has made me think about which is best environmentally, some turf on your roof or some ST/PV.
It gets into the tricky area of what is 'environment', and how do we value it.

Tom
Was being just a little facetious calling it turf, but on one of my serious notes, flat roofs could make a comeback. I know they have a chequered history in the UK (mainly because of our inability to know the difference between value and price and the building industry being slap-dash), but it is a dreadful waste of space having a traditional roof, especially with small gardens. Be a great place to camp out in the right weather too.

One thing humans excel at is destroying habitats and pushing other species out, which will be to our great detriment. The rate of species extinctions at present is estimated at 100 to 1000 times "background" or average extinction rates in the evolutionary time scale of planet Earth (source: Extinction rates by J.H.Lawton and R.M.May). Biologist E. O. Wilson estimated in 2002 that if current rates of human destruction of the biosphere continue, one-half of all species of life on earth will be extinct in 100 years.

Seems to me that anything we can do to reverse this trend and harmonise human activity with natural systems should be done as soon as possible. Turning our cities from sterile deserts into wildlife friendly places is one step and greening them with the extensive use of green roofs is one method.

One of my favourite architects, Friedensreich Hundertwasser, went even further with the idea of "tree tenants", where a window is given over to a tree:

Tree tenants can be seen from far away and benefit many people, also those who walk around the house and dwell nearby. The tree tenant symbolizes a turn in human history because he regains his rank as an important partner of man. The relationship man - vegetation must have again religious dimensions. Only if you love the tree like yourself you will survive. We suffocate in our cities through poison and lack of oxygen. We destroy systematically the vegetation which gives us life and lets us breathe. We walk alongside grey and sterile facades of houses. It is our duty to reinstall the rights of nature with all means. Cars have chased the trees up into the storeys of houses. We suffer daily from the aggressivity and the tyranny of our vertical sterile high walls. But streets in the cities will become green valleys where man can breathe freely again. Tree tenants dwell inside the walls of the house in an area of about one square meter behind the windows. The windows are set back and you can look at the tree tenant and outside. The tree tenant has one cubic meter of soil at his disposal and can become quite big. The tree tenant pays his rent in much more valuable currency than the humans.

1. Tree tenants create oxygen.
2. Tree tenants improve the city climate and the well being of dwellers.
They bring the needed moisture into the desert climate of the city, reduce the dry-humid and the cold-warm contrast.
3. Tree tenants act like vacuum cleaners. More so. They swallow even the finest and poisonous dust. There is less dust in the apartment and in the street.
4. Tree tenants swallow noise. They reduce the echoes of the city noise and create quietness.
5. Tree tenants protect you from outside view like curtains and create shelter.
6. Tree tenants give shadow in summer but let sunlight through in winter when leaves have fallen.
7. Butterflies and birds come back.
8. Beauty and joy of life come back. Living quality is improved with this piece of own nature.
9. The tree tenant is a symbol of reparation towards nature which is extremely visible. We restore to nature a tiny piece of the huge territories which man has taken away from nature illegally.

The tree tenant is a giver. It is a piece of nature, a piece of homeland, a piece of spontaneous vegetation in the anonymous and sterile city desert, a piece of nature which can develop without the rationalist control of man and his technology.

—Friedensreich Hundertwasser

All totally gorgeous! You and Hundertwasser have answered burgers' original question conclusively.

I'd add to H's theme: no reason why humans' doings can't leave the planet actually better off, than if nothing had been done. So much focus, even on GBF, is on the assumption that any kind of human doing is inherently damaging, and that the best we can do is slow the rate of damage by a few %age points by 2050 or whenever.

Not so - by aligning with nature consciously, assisting nature in the giant clean-up task that we've created, rather than just adding more mess (albeit at a slower rate - perhaps), then it's not merely a matter of 'duty' (Hundertwasser) but a matter of self-interest, survival of human (and maybe all) life on earth.

The levels of Permaculture (and its ally Transition) that go beyond mere 'better gardening', are about this, looking to the day when humans can create mighty infrastructure projects, if they wish, on the scale of airports and Crossrails (or future equivalent) confident in the knowledge and understanding that these can help nature to speed up the recovery (so the more ambitious the project the better) to 10s and 100s of yrs, instead of the 100s and 1000s and 10000s that nature would take, unaided. We humans can't wait for the latter.

In the past we've presumed to 'master' nature, which was a bit silly seeing we ARE nature. Maybe in future we don't have to become all humble, but can change the script to one where clever humans actively help nature to be herself and do her thing even better than she can 'naturally'. Why not? - because we ARE nature!

Posted By: SteamyTeaElder grows anywherehttp:///forum114/extensions/Vanillacons/smilies/standard/bigsmile.gif" alt="" title="" >

But Gavin joining the debate has made me think about which is best environmentally, some turf on your roof or some ST/PV.
It gets into the tricky area of what is 'environment', and how do we value it.

a bit of both could be possible.

we're looking at a job at the moment where they already have green roofs on the other roofs, and the roof we're looking at is the same structure, so we've given them an option for using a version of a flat roof mounting system with no roof penetration, and using a form of moss covered green roof covering as balast.

This place has no connection to the mains drains, and is using an odd box section soakaway all round the base to soak away all rain (which I'm a bit sceptical about) so having a green roof to soak up rain and reduce the rate of run off makes a lot of sense.

This wouldn't be possible on most roofs though, as probably 95% of roofs in this country are too steep and / or too weak to be used as green roofs, whereas most are suitable for PV / thermal.

Posted By: JoinerAny UK planners looking in will be foaming at the mouth now!http:///forum114/extensions/Vanillacons/smilies/standard/wink.gif" alt="" title="" >

in what way?

oh right. Odd that there's so few of them around then - I presume most people simply ignore them, or that it's more likely that a few isolated planners love them, most don't.

From my experience in London a lot of green roofs get put on planning drawings and then they get value engineered out of the scheme by contractors. Less and less so now though.

I don't think Hundertwasser was using the word religion in the organised sense. I'm as atheist as they come but I think I understand what he was getting at; that we need to regard trees as sacred. They are after all the lungs of our biosphere. But more than that, we need to stop pretending we're separate to our biosphere. Our biosphere is arguably a living entity in itself, a self-regulating complex system (aka Gaia theory). In that sense trees and humans are part of the same self-regulating system, one and the same. Hence to love trees like we love ourselves is the only sensible course of action if we'd like to survive.

Indeed. And yes, there's nothing like a good tree.

Posted By: seascapebut won't the leaves drop off at certain times of the year?

Good point, especially if your local authority is in Norfolk, the ones that cut the conker trees down.